I've used Nikon's top-end D3, and it's a fine instrument, but far more camera than I'd need. The D3x, just mistakenly announced today, would be even further overkill. Never mind the various medium format cameras and the upcoming ultra-luxe Leica S2.
So, if I were suddenly independently wealthy, I'd still get myself a new Nikon, but it would be the D700, which packs most of the power of the D3, including its wonderful low-noise, high-sensitivity full-frame sensor, into a smaller (we're talking relatively smaller here) package. I've also tried the similarly sized D300, so I think the D700 would fit better in my hand.
And I'd buy some great lenses too, of course, because that's where money is best worth spending. I'm still using an inexpensive but quality lens I bought in 1995, while the camera it went with is long, long gone.
Finally, I'd travel to beautiful places with my family, to make photos with them.